USED This 1 groove sheave measures; 3" for the outer diameter, 1 3/5" for the inner diameter which is measured from the bottom of the groove according to standard pulley measurements. The sheave measures 1 1/2" thick excluding the hub. The hub itself measures 1/2" for the inner diameter where the shaft would be located. One side of the hub has a 3/16" high threaded area which has a 1 1/8" outer diameter. The groove on the inside shaft opening measures 3/16" by 1/8". The original manufacturer and part number are unknown.